"Well, it's a hot topic because people go to the pump, and they look around and they say, 'I don't know which one to do,'" Champion said.

Fueling a vehicle is simple, but small engines are a different story. When the ethanol content changed, service managers, like Larry Almgren at Pruitt Outdoor Power, have questions.

"Almost all manufacturers (of small engines) say you can use 10 percent ethanol," Champion said.

E-15 and E-85 should not be used for small engines, experts said, and E-10 can be used up to 30 days of purchase if it stored in a sealed container. If the fuel sits too long, the ethanol will absorb water from the air and separate, feeding small engines water and alcohol instead of healthy fuel.

Almgren said buying additives can help fuel last longer.

"They do have additives that help with that water absorption, and the separation and the losing the octane issues," Almgren said.

If you want to make sure your gasoline contains 10 percent ethanol, Almgren said there are ways to test it.